Neither the Tumor Necrosis Factor α-308 A/G Polymorphism nor the α2-macroglobulin Polymorphism was Associated with Late-onset Alzheimer's disease in the Chinese Population

Late-onset Alzheimer's disease (LOAD) is the most common cause of dementia in the elderly. It is a complex and genetically heterogeneous disorder. Epidemiological studies demonstrated that nonsteroidal anti-inflammatory drugs could prevent or delay the onset of LOAD suggesting inflammation may be involved in AD. Tumor necrosis factor (TNF) is a potent immunomodulator and it might increase the production of amyloid β(Aβ), which makes it an appropriate AD candidate gene. α2 macroglobulin (A2M) is a serum protease inhibitor and a major low-density lipoprotein receptor-related protein (LRP) ligand. It can bind Aβ and mediate its clearance and degradation, suggesting it might be another AD candidate gene. In the present study, we analyzed the a 5 bp Ins/Del polymorphism of A2M gene (A2M-2), TNF α-308 A/G polymorphism and apolipoprotein E (APOE) polymorphisms of 67 sporadic late-onset AD patients and 142 normal elderly controls in the Chinese population. Our data showed that the APOE ε4 allele frequency in AD was significantly higher than that in the normal controls (χ² = 11.66, P < 0.01) neither the frequencies of genotypes nor alleles of the TNF α-308 A/G and A2M polymorphisms were significantly different between AD and controls, suggesting the two polymorphisms were not risk factors to LOAD in Chinese.